[PATCH net-next v3 05/14] dpll: dpllsim: Add support to set input pin state

[Petr Oros <poros@redhat.com>]

Add support for setting the state of input pins on the device.
Implement the state_on_dpll_set callback for input pins and advertise
the state-can-change capability for them, so that userspace can move a
pin between the states valid for the device mode. The core checks the
capability only, the states a mode allows are up to the driver: in
automatic mode a pin is selectable or disconnected, in manual mode
connected or disconnected, as Documentation/driver-api/dpll.rst
describes them. The device reports automatic mode, so connected is
refused with -EINVAL and an extack message. The check is written for
both modes already, so that manual mode has nothing to add to it when
it arrives. The driver stores the requested state and reports it back
unchanged, it does not act on it yet. Output pins keep reporting their
state only.

Signed-off-by: Petr Oros <poros@redhat.com>
---
v3:
- refuse pin states that are not valid in the device mode, so that
  connected is refused in automatic mode, the mode the device reports,
  with an extack message (Ivan Vecera)
- the Acked-by of v2 is not carried over, the callback changed

v2: https://lore.kernel.org/all/20261105151852.1844305-6-poros@redhat.com/
v1: https://lore.kernel.org/all/20261103093910.596225-6-poros@redhat.com/
---
 drivers/dpll/dpllsim/dpll.c | 42 +++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/dpll/dpllsim/dpll.c b/drivers/dpll/dpllsim/dpll.c
index a1d5921fb8d017..794020d0c112e8 100644
--- a/drivers/dpll/dpllsim/dpll.c
+++ b/drivers/dpll/dpllsim/dpll.c
@@ -104,10 +104,46 @@ static int dpllsim_pin_state_get(const struct dpll_pin *pin, void *pin_priv,
 	return 0;
 }
 
+/*
+ * The states a user may request depend on the device mode: connected and
+ * disconnected select and deselect the reference in manual mode, selectable
+ * and disconnected offer a pin to or withdraw it from the automatic
+ * selection. The core checks the state-can-change capability only.
+ */
+static bool dpllsim_pin_state_valid(const struct dpllsim_dev *sim,
+				    enum dpll_pin_state state)
+{
+	if (state == DPLL_PIN_STATE_DISCONNECTED)
+		return true;
+	if (sim->mode == DPLL_MODE_MANUAL)
+		return state == DPLL_PIN_STATE_CONNECTED;
+	return state == DPLL_PIN_STATE_SELECTABLE;
+}
+
+static int dpllsim_pin_state_set(const struct dpll_pin *pin, void *pin_priv,
+				 const struct dpll_device *dpll,
+				 void *dpll_priv, enum dpll_pin_state state,
+				 struct netlink_ext_ack *extack)
+{
+	struct dpllsim_pin *sim_pin = pin_priv;
+	struct dpllsim_dev *sim = sim_pin->dev;
+
+	guard(mutex)(&sim->lock);
+	if (!dpllsim_pin_state_valid(sim, state)) {
+		NL_SET_ERR_MSG_FMT(extack, "Pin state not valid in %s mode",
+				   sim->mode == DPLL_MODE_MANUAL ?
+				   "manual" : "automatic");
+		return -EINVAL;
+	}
+	sim_pin->state = state;
+	return 0;
+}
+
 static const struct dpll_pin_ops dpllsim_input_pin_ops = {
 	.frequency_get = dpllsim_pin_frequency_get,
 	.direction_get = dpllsim_pin_direction_get,
 	.state_on_dpll_get = dpllsim_pin_state_get,
+	.state_on_dpll_set = dpllsim_pin_state_set,
 };
 
 static const struct dpll_pin_ops dpllsim_output_pin_ops = {
@@ -149,6 +185,12 @@ static void dpllsim_pin_props(struct dpllsim_pin *pin,
 		prop->freq_supported_num = ARRAY_SIZE(dpllsim_freq_ext);
 		break;
 	}
+
+	/* Capabilities follow the ops the pin is served by */
+	if (dpllsim_pin_select_ops(pin) == &dpllsim_input_pin_ops)
+		prop->capabilities = DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE;
+	else
+		prop->capabilities = 0;
 }
 
 static bool dpllsim_pin_frequency_valid(struct dpllsim_pin *pin)
-- 
2.56.0